Fire retarding composition for use in wood composite panels

ABSTRACT

The current invention concerns a fire retardant composition for use in wood composite panels, either comprising a fire retardant agent or an intumescent formulation, whereby the pH of a 10% aqueous solution of said composition lies between 3.5 and 8.5. The present invention also provides for a specific use of the composition in fire retardant wood composite panels, the respective method for producing those panels, as well as the resulting wood composite panels themselves.

TECHNICAL FIELD

The invention pertains to the technical field of fire retardantcompositions for use in wood composite panels.

BACKGROUND

Wood composite panels are widely used in the construction business. Bothwood as well as these wood-base materials have to meet extensiverequirements with regard to flameproof properties. In Europe, variousstandards and requirements are introduced which allow comparison of fireproperties of construction materials (e.g. Euroclasse EN 13501-1).Characteristics such as hardly inflammability, ignitability, flamespread, calorific value as well as the development of smoke and burningdroplets of the material are all taken into account when classifying aconstruction material in these classes.

In order to meet these requirements and to meet the highest qualitystandards, wood composite panels are during their production oftensupplemented with compositions with fire retarding characteristics andoptionally smoke suppressors.

U.S. Pat. No. 8,715,540 for instance describes a fire retardantcomposition for reducing the amount of burning that occurs to a materialas well as the smoke density which is produced. The composition may beadded to construction material.

EP 2 586 849 is directed to an aqueous composition comprisingmonoammonium dihydrogen phosphate as flame retardant. The composition isused during the production of wood composite panels to create flameretarding wood composite panels.

WO 02/102926 describes a fire retardant composition consistingessentially of tributylamine, borax and monoammonium phosphate, which inaqueous solution has a resulting pH of 6.0 to 8.5 and which is used inthe production of fiberboards by spraying.

U.S. Pat. No. 4,725,382 concerns a water soluble fire retardantcomposition that utilizes pH control to afford a fire retardant materialof low corrosiveness and comprises boric acid, monoammonium phosphateand diammonium phosphate. pH of an aqueous solution is about 6.7 to6.95.

The production of these wood composite panels typically makes use of anadhesive or resin to provide cohesion to the wood particles or fibers.Addition of additives such as fire retardant compositions can have animpact on the functionality of these resins (e.g. lower bond strength).As a consequence, higher amounts of resins are sometimes needed in orderto ensure good cohesion of the articles and thus good quality endproducts.

There is thus a need in the art for an improved manner of producing fireretardant and smoke suppressing wood composite panels, as well as a needfor better performing fire retardant/smoke suppressing compositionswithout influencing the functionality of resins. The current inventionaims to provide a solution for the latter by fine-tuning the fireretardant composition in function of the chosen resin.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides for a fire retardantcomposition according to claim 1. This composition is particularlyuseful for use in wood composite panels. The pH of the composition hasbeen meticulously adapted by the addition of one or more pH regulators,in order to provide a good compatibility with the resins used during theproduction of the wood composite materials. Moreover, the pH may befurther controlled, based on the specific resin used during theproduction. By controlling the pH of the fire retardant composition to avery specific and predetermined range, the inventors of the currentinvention found that the bond strength of the resin was positivelyinfluenced. This even resulted in a lower resin consumption which on itsturn has a positive influence on cost.

In a second aspect, the present invention provides for a fire retardantcomposition according to claim 2. This composition is particularlyuseful for use in wood composite panels and comprises an intumescentformulation. While intumescents are known to be used as fire retardant,their use in wood composite panels has to date been limited to coatingsof the finished panels, because of their incapability with the resinsused for the production of the panels. These panels are typicallyproduced of cellulose containing material such as wood chips, which arebound together by a resin and pressed. Previously, when adding theintumescent formulation to the cellulose containing material and resin,the formulation and resin were found to react. This led to an earlyactivation of the intumescent formulation as well as degradation of theresin. The inventors of the current invention now found that by adaptingthe pH of the composition by the addition of one or more pH regulators,the intumescent formulation could also be applied in the core of a woodcomposite panel. By controlling the pH of the fire retardant compositionto a very specific and predetermined range, the inventors of the currentinvention found that the unwanted activation of the intumescentformulation and degradation of the resin was prevented. The intumescentformulation and resin remained stable during the production of said woodcomposite panels. This allows for a use of the composition within thepanel rather than as a subsequent coating once the panel has beenproduced. As a consequence, the production of the panels is moreefficient and cost effective.

In a third aspect, the present invention provides for a specific use ofthe composition in fire retardant wood composite panels according toclaim 22, the respective method for producing those panels in claim 23,as well as the resulting panels according to claim 24. The resultingpanels comply with various fire test standards (ASTM, EN, DIN, BS, NF P)for construction products.

DETAILED DESCRIPTION OF THE INVENTION

The present invention concerns a fire retardant composition, its use inwood composite panels, the method for production thereof and theresulting wood composite panel.

Unless otherwise defined, all terms used in disclosing the invention,including technical and scientific terms, have the meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. By means of further guidance, term definitions are included tobetter appreciate the teaching of the present invention.

As used herein, the following terms have the following meanings:

“A”, “an”, and “the” as used herein refers to both singular and pluralreferents unless the context clearly dictates otherwise. By way ofexample, “a compartment” refers to one or more than one compartment.

“About” as used herein referring to a measurable value such as aparameter, an amount, a temporal duration, and the like, is meant toencompass variations of +/−20% or less, preferably +/−10% or less, morepreferably +/−5% or less, even more preferably +/−1% or less, and stillmore preferably +/−0.1% or less of and from the specified value, in sofar such variations are appropriate to perform in the disclosedinvention. However, it is to be understood that the value to which themodifier “about” refers is itself also specifically disclosed.

“Comprise”, “comprising”, and “comprises” and “comprised of” as usedherein are synonymous with “include”, “including”, “includes” or“contain”, “containing”, “contains” and are inclusive or open-endedterms that specifies the presence of what follows e.g. component and donot exclude or preclude the presence of additional, non-recitedcomponents, features, element, members, steps, known in the art ordisclosed therein.

The recitation of numerical ranges by endpoints includes all numbers andfractions subsumed within that range, as well as the recited endpoints.

The expression “% by weight”, “weight percent”, “% wt” or “wt %”, hereand throughout the description unless otherwise defined, refers to therelative weight of the respective component based on the overall weightof the formulation. The expression “% by dry weight of the composition”is to be understood as the relative weight of the respective componentbased on the overall weight of the dry matter of the formulation.

The expression “wood composite panels” refers to a range of derivativewood products which are manufactured by binding or fixing the strands,particles, fibers, or veneers or boards of wood, together withadhesives, resins of bico-fibers, to form composite materials.Typically, engineered wood products are made from the same hardwoods andsoftwoods used to manufacture lumber. Sawmill scraps and other woodwaste can be used for engineered wood composed of wood particles orfibers, but whole logs are usually used for veneers, such as plywood,medium density fiberboard (MDF) or particle board. Some engineered woodproducts, like oriented strand board (OSB), can use trees from thepoplar family, a common but non-structural species.

Alternatively, it is also possible to manufacture similar engineeredbamboo from bamboo; and similar engineered cellulosic products fromother lignin-containing materials such as rye straw, wheat straw, ricestraw, hemp stalks, kenaf stalks, or sugar cane residue, in which casethey contain no actual wood but rather vegetable fibers.

Hence, wood composite panels may include, but are not limited toplywood, fiberboard, oriented strand board (OSB) laminated timber orveneer, particle board, panel board, or medium density fiberboard (MDF),high density fiberboard (HDF) or wood and cellulose fiber insulation.

The term “dry” as is used herein in connection with a composition of theinvention, or with individual components of a composition of theinvention, means that water, and other aqueous and non-aqueous liquids,are not an ingredient or component of the composition, but that the drycomposition may, or may not, include some moisture. The amount ofmoisture that may be present in a dry composition of the inventionpreferably is less than about 1% by weight, more preferably less than0.5% by weight, and more preferably is less than about 0.1% by weight,and most preferably is about 0% by weight. A dry composition of theinvention may, for example, be in the form of a powder, granules,particles, pellets and/or the like. The various forms that drycompositions may take are known by those having ordinary skill in theart.

The phrase “aqueous” as is used herein in connection with a compositionof the invention means that the composition has been at least partiallydissolved in a solvent such as water, or that a dispersion has beenproduced.

The term “composition” as is used herein means a product that resultsfrom the combining of more than one ingredient.

The term “fire retardant agent” as used herein is to be understood as anagent which when added to a wood composite material, is able to providefire retardancy characteristics to said material. Fire retardancy isdefined by the reduction of release of energy, spread of flame and speedat which the flame spreads during a fire.

The term “smoke suppressing agent” is to be understood as an agentwhich, when added to a wood composite material, is able to reduce thesmoke production or density of the material when heated or burning.

The term “intumescent formulation” is to be understood as a formulationwhich, when added to a wood composite material, swells as a result ofheat exposure, thus increasing in volume. And thereby protecting thewood composite material and/or preventing further spreading of the fire.Intumescents are typically used in passive fire protection.

In a first aspect, the invention provides a fire retardant compositionfor use in wood composite panels, said composition comprising at leastone fire retardant agent, a pH regulating compound and optionally asmoke suppressing agent, whereby the pH of a 10% aqueous solution ofsaid composition lies between 3.5 and 8.5, more preferably between 4.0and 8.0.

The inventors of the current invention found that by regulating the pHof the composition to a narrow and predefined range by use of a pHregulating compound, an optimal compatibility with the resins usedduring the production of the wood composite panels is obtained. The pHof the composition is determined in a 10% aqueous solution of thecomposition, which allows standardization amongst all compositionscomplying with the scope of the current invention. The pH can bemeasured by any suitable method know in the art. By preference the pH ismeasured by potentiometry.

Said fire retardant agent is preferably chosen from the group ofammonium (poly)phosphates such as monoammonium dihydrogen phosphate(MAP), di-ammonium hydrogen phosphate (DAP, both technical andfertilizer grade) or ammonium polyphosphate (of various chain lengths),melamine phosphate, melamine polyphosphate; ammonium sulfate; ammoniumchloride; ammonium sulfamate; guanidine phosphate; guanidine hydrogenphosphate; guanidine sulfamate; guanidine carbonate; methylene urea,urea phosphate and alkaline earth phosphates or any mixture thereof.

By preference, the total concentration of the fire retardant agent inthe composition is between 25 and 100% by dry weight of saidcomposition, more preferably between 25 and 98% by dry weight of saidcomposition. Below this ratio, the composition will not providesufficient fire retardant protection when added to wood compositeproducts.

In one embodiment, said 10% aqueous solution of said fire retardantcomposition has a pH which lies between 5.0 and 7.0 when the resin ischosen from the group of urea-formaldehydes, said resin being preferablymelamine urea-formaldehyde. In another embodiment, said resin is chosenfrom the group of phenol-formaldehyde, in which case the 10% aqueoussolution has a pH between 6.0 and 8.0. In another embodiment, the resinis chosen from the group of isocyanates, in which case the 10% aqueoussolution of said fire retardant composition has a pH between 4.0 and6.0. These pH values are obtained by use of a pH regulating compound andare specifically chosen to minimalize the influence of the fireretardant composition on the functionality of the chosen resin.

In one embodiment, said one or more fire retardant agents in thecomposition act uniquely as fire retardant. In another embodiment, saidfire retardant agents may have a dual function, and may for instancealso act as a pH regulating compound. This is specifically the case whena high concentration of pH regulating compound is needed in order tocomply with the desired pH range of the current invention.

Typically, when the concentration of the pH regulating compound exceedsa total concentration of 10% by dry weight of the composition, care istaken to choose a pH regulating compound which may simultaneouslyprovide fire retarding and/or smoke suppressing activity within thecomposition, in order to prevent a lesser active composition. Examplesof pH regulating compounds with dual action are for instancemonoammonium or diammonium phosphate. When the latter are used toregulate the pH, a second fire retardant agent will always be present inthe composition.

By preference, said pH regulating compound may be chosen from the groupof mono-ammonium dihydrogen or di-ammonium hydrogen phosphate (bothtechnical and fertilizer grade), guanidine phosphate, guanidine hydrogenphosphate, guanidine carbonate, ammonium or aluminum sulfate, magnesiumphosphate, magnesium ammonium phosphate, monoethanolamine, phosphoricacid, sulfamic acid, mono or di calcium phosphate, mono-, di-, trialkalimetal phosphates, ammonia or ammonia solution, melamine, or any mixturethereof.

The amount of the pH regulating compound which needs to be added to thecomposition is thus determined, that the pH of the final composition,when in a 10% aqueous solution lies between 3.5 and 8.5, more preferablybetween 4.0 and 8.0.

By preference, the total concentration of said pH regulating compoundsis between 2 and 60% by dry weight of the composition. As mentioned,when the total concentration of the pH regulating compound exceeds 10%,it will be opted to use a pH regulating compound which has a dualfunction, either as a fire retardant agent or smoke suppressing agent orboth, in order to ensure the activity of the composition in terms offire retardant (and smoke suppressing) activity.

The composition of the current invention may optionally comprise a smokesuppressing agent, which preferably is present in a total concentrationof between 0 and 40% by dry weight of said composition; more preferablybetween 0 and 25% by dry weight of said composition, even morepreferably in a concentration of between 1 and 20% by dry weight of saidcomposition.

Said smoke suppressing agent, when present, is chosen from the group ofborate minerals, boric acid or a salt thereof such as zinc borate, borax(decahydrate or pentahydrate), disodium octaborate (anhydrous ortetrahydrate); calcium or magnesium phosphates (e.g. monocalciumphosphate, dicalcium phosphate), magnesium ammonium phosphate (anhydrousor hydrate) and magnesium hydroxide or a mineral thereof such asbrucite; or any mixture thereof.

By preference, borate minerals are ulexite, colemanite, kernite, howliteor probertite. The inventors of the current invention found that theseminerals have good smoke suppressing function. Because of their naturalnature, they exhibit no or only very low toxicity which makes themparticularly useful for use in the fire retardant compositions accordingto the current invention. As a consequence, these minerals are goodalternatives for e.g. more toxic smoke suppressors such as boric acid ordisodium octaborate (DOT) or can be used to reduce the amount of thesecomponents when present in the fire retardant compositions according tothe current invention.

In a second aspect, the invention provides a fire retardant compositionfor use in wood composite panels, whereby said composition comprises anintumescent formulation as fire retardant agent, wherein the pH of a 10%aqueous solution of said composition lies between 3.5 and 8.5, morepreferably between 4.0 and 8.0.

While intumescent formulations are used for protection of structuralsteel and after treatment of natural wood or wood panels, whereby theseformulations are applied as a coating, mass incorporation of intumescentformulations in the surface and the core of wood and cellulose basedmaterials has shown to be a difficult process. Intumescent formulationsoften show incompatibility with resins used in such wood panels leadingto dysfunctional panels. The inventors of the current invention nowfound that by regulating the pH of the composition to a narrow andpredefined range by use of a pH regulating compounds, an optimalcompatibility with the resin used during the production of woodcomposite panels can be obtained. The pH of the composition isdetermined in a 10% aqueous solution of the composition, which allowsstandardization amongst all compositions complying with the scope of thecurrent invention.

The total concentration of said fire retardant agent in the fireretardant composition is preferably between 25 and 100% by dry weight ofsaid composition, more preferably between 25 and 98% by dry weight ofsaid composition. Below this ratio, the composition will not providesufficient fire retardant protection and intumescent capabilities whenadded to wood composite products.

By preference, said intumescent formulation comprises a mixture of oneor more acid components, one or more spumific agents, a pH regulatingcompound and optionally one or more carbonific components, a bindingcomponent and/or an ablative acting fire retarding component. Saidformulation undergoes thermal degradation upon heating, producing athermally stable, foamed and multicellular residue called intumescentchar. The acid source is preferably an inorganic acid and can be eitherreadily available or formed from a precursor upon heating. Thecarbonific components are preferably polyhydric compounds rich in carbonatoms. Said spumific agent produces non-flammable gases whichparticipate in the formation of an expanded intumescent char.

Preferably the concentration of the acid components is between 10.0 and95.0% by dry weight of said formulation, more preferably between 30.0and 75.0% by dry weight of said formulation, even more preferablybetween 50.0 and 70.0% by dry weight of said formulation. Theconcentration of the carbonific components when present is preferablybetween 0.05 and 60.0% by dry weight of said formulation, morepreferably between 1% and 60.0% by dry weight, more preferably between10.0 and 50.0% by dry weight of said formulation, even more preferablybetween 10.0 and 30.0% by dry weight of said formulation. Theconcentration of the spumific agents is preferably between 0.2 and 80.0%by dry weight of said formulation, more preferably between 0.1 and 50.0%by dry weight of said formulation, even more preferably between 0.1 and30.0% by dry weight of said formulation. The concentration of thebinding component, if present, is preferably between 0.2 and 40.0% bydry weight of said formulation, more preferably between 0.5 and 20.0 bydry weight of said formulation and the concentration of the ablativeacting fire retarding component, if present, is preferably between 0.2and 20.0% by dry weight of said formulation, more preferably between 0.5and 10.0% by dry weight of said formulation. Outside these ranges, thecomposition will not provide sufficient fire retardant protection whenadded to wood composite products. Moreover, the intumescent activity ofthe formulation will be suboptimal outside these ranges.

In a preferred embodiment, the intumescent formulation used in theframework of the current invention will comprise of:

-   -   between 10.0 to 95.0% of acid components by dry weight of the        formulation,    -   between 0.05% to 60.0% of carbonific components by dry weight of        the formulation,    -   between 0.2 to 80.0% of spumific components by dry weight of the        formulation,    -   optionally between 0.2 and 40.0% of binding component by dry        weight of the formulation, and    -   optionally between 0.2 and 20.0% of ablative acting fire        retarding component by dry weight of the formulation.

In one embodiment, said acid components are chosen from the group ofphosphoric acid, sulfuric acid, boric acid, monoammonium dihydrogenphosphate, diammonium hydrogen phosphate, ammonium polyphosphate,ammonium sulfate, ammonium halides, urea phosphate, guanyl ureaphosphate, guanidine carbonate, melamine phosphate, melaminepolyphosphate, melamine cyanurate, pentaerythritol phosphate, guanidinephosphate and other amine and amide phosphates.

In a further or other embodiment, said carbonific components are chosenfrom the group of glucose, arabinose and other monosaccharides, lactose,maltose and other disaccharides, starch, cellulose, dextrin and otherpolysaccharides, sorbitol, erythritol, pentaerythritol,dipentaerythritol, tripentaerythritol, other polyhydric alcohols andother substances susceptible to dehydration or deamination.

In a further or other embodiment, said spumific agents are chosen fromthe group of melamine, melamine cyanurate, melamine phosphate, melaminepolyphosphate and other melamine-based compounds, guanidine phosphate,guanidine sulfate, guanidine carbonate and other guanidine salts.

As a binder in said formulation, a polymer dispersion of acrylate,styrene-acrylate, vinyl acetate, vinyl acetate-ethylene, polyvinylethersand polyurethanes is possible. Also ablative acting fire retardantagents such as aluminum hydroxide, aluminum oxide hydroxide, magnesiumhydroxide, colemanite or ulexite can be involved in said formulation.The efficiency of the intumescent formulation can be increased bysynergistic effects taking place between the different components. Otheradditives, like titanium dioxide, can modify the intumescent charstructure, yielding a better fire retardancy.

By preference, said 10% aqueous solution of said fire retardantcomposition has a pH which lies between 5.0 and 7.0 when the resin ischosen from the group of urea-formaldehydes, said resin being preferablymelamine urea-formaldehyde. In another embodiment, said resin is chosenfrom the group of phenol-formaldehyde, in which case the 10% aqueoussolution has a pH between 6.0 and 8.0. In another embodiment, the resinis chosen from the group of isocyanates, in which case the 10% aqueoussolution of said fire retardant composition has a pH between 4.0 and6.0. These pH values are obtained by use of a pH regulating compound andare specifically chosen to minimalize the influence of the fireretardant composition on the functionality of the chosen resin.

In one embodiment, said one or more acid components, carbonificcomponents and spumific components only perform a single function. Inanother embodiment, said components may have a dual function, and mayfor instance also act as a pH regulating compound. This is specificallythe case when a high concentration of pH regulating compound is neededin order to comply with the desired pH range of the current invention.Typically, when the concentration of the pH regulating compound exceedsa total concentration of 10% by dry weight of the composition, care istaken to choose a pH regulating compound which may simultaneously act asan acid component, a carbonific component or a spumific component, inorder to prevent a lesser active composition. Examples of pH regulatingcompounds with dual action are for instance monoammonium or diammoniumphosphate.

By preference, said pH regulating compound may be chosen from the groupof mono-ammonium dihydrogen or di-ammonium hydrogen phosphate (bothtechnical and fertilizer grade), guanidine phosphate, guanidine hydrogenphosphate, ammonium or aluminum sulfate, magnesium phosphate, magnesiumammonium phosphate (anhydrous or hydrate), monoethanolamine, phosphoricacid, sulfamic acid, mono or di calcium phosphate, mono-, di-, trialkalimetal phosphates, ammonia or ammonia solution, melamine or any mixturethereof.

The amount of the pH regulating compound which needs to be added to thecomposition is thus determined, that the pH of the final composition,when in a 10% aqueous solution lies between 3.5 and 8.5, more preferablybetween 4.0 and 8.0.

By preference, the total concentration of said pH regulating compoundsis between 2 and 60% by dry weight of the composition. As mentioned,when the total concentration of the pH regulating compound exceeds 10%,it will be opted to use a pH regulating compound which has a dualfunction in the intumescent formulation.

The compositions as described above, are a particulate dry matter, suchas a powder, ground, pulverized or otherwise finely dispersed solidparticles, whether not compressed (i.e. in loose form) or compressedtogether to produce a solid structure, such as a solid structure in theshape of a pill, powder, pellet, stick or the like.

By preference, for powders, at least 90% of the particles present in thecompositions will have a particle size which is smaller than 200 μm. Inanother or further embodiment, at least 90% of the particles present inthe compositions when in a dry formulation will have a particle size ofless than 60 μm. More preferably, at least 70 of the particles will havea particle size of less than 40 μm.

Methods to determine the particle size are known in the art. Aparticularly suitable method is laser diffraction.

The compositions may equally be in a liquid form, such as a dispersionor suspension, a solution, an emulsion or a slurry. By preference, wateris used as solvent.

Such liquid can be obtained by use of a particulate dry mattercomposition according to the current invention and thereby producing anaqueous solution, dispersion or slurry. This could for instance be doneon the site of the wood composite panel production, just prior to addingthe composition to the production line. Another possibility is theready-to-use production of a dispersion according to an embodiment ofthe current invention, by means of one or more tanks provided with amixing device suitable for making a dispersion. The constituents of thecompositions according to the current invention are added to a mixingtank with the addition of water, after which an aqueous solution ordispersion is made.

When used as a dispersion, the compositions according to the currentinvention may be further comprising a thickener and/or viscosityregulator and/or a wetting agent. Said thickener may be an organic or aninorganic thickener to adjust the viscosity of the dispersion to apredefined viscosity target. Suitable organic include cellulosicmaterial and gums such as xanthan gum. If very fine dispersions areachieved, inorganic thickeners such as, but not limiting to, claythickeners such as bentonite or sepiolite thickeners are suited for thecurrent invention. Addition of these compounds prevents settlement ofparticles in dispersions according to the current invention, henceaiding to prolong the shelf life of the compositions.

The compositions according to the current invention may further comprisea detection compound and/or an antimicrobial or antifungal compound.

Said detection compound can be understood as a tracer, in an amount thatis sufficient to permit a determination by one or more detectionprocesses before or after a material has been exposed to flame or fire(or other burning), of whether or not a composition of the invention hadbeen applied to the material prior to the material being exposed to theflame or fire (or other burning), and if so, whether the composition hadbeen applied to the material properly.

An antimicrobial and/or antifungal compound can be understood as anysubstance which may inhibit growth of microorganisms such as bacteria orfungi in the wood composite panels when treated with the compositingaccording to the current invention.

In a third aspect, the invention provides a use of said fire retardantcomposition according to one of the embodiments as described above inwood composite panels, whereby said fire retardant composition and itspH is specifically chosen in function of the resin that is used in thewood composite panel. When used as a dispersion, the compositions can beused as they are. In case the compositions comprise a powder, they arepreferably diluted in water according to a ratio between 40/60 and70/30, preferably between 50/50 and 60/40. The compositions are mixedwith or sprayed upon cellulose containing material, preferably prior tosaid cellulose containing material begin pressed to a panel in thepresence of a resin.

The invention also provides a method for the production of woodcomposite panels comprising a fire retardant composition according toone of the embodiments as described above and a resin, whereby saidresin is chosen from the group of melamine-urea-formaldehydes,phenol-formaldehydes or isocyanates and whereby said fire retardantcomposition either comprises at least one fire retardant agent or anintumescent formulation, whereby the pH of a 10% aqueous solution ofsaid composition lies between 3.5 and 8.5, more preferably between 4.0and 8.0.

Said method for the production of said composite panel boards comprisesthe following steps: the shredding of wood into wood strips and/or thechipping of wood into smaller wood chips, the addition of said fireretardant composition and said resin to said wood strips or chips,preferably by spraying the fire retardant composition and resin on thewood strips or chips, the orientation of said wood strips or chips on abelt or a wire caul into a mat, the subsequent heat compression of thismat, resulting in a compressed panel, finally cutting this compressedpanel to the desired panel size.

In one embodiment, the production of wood composite panel boardscomprises the use of melamine urea-formaldehyde (MUF) orurea-formaldehyde (UF) as a resin, in this case the pH of a 10% aqueoussolution of the composition according to one of aforementionedembodiments is preferably between 5.0 and 7.0. In another embodiment,preferably when an intumescent formulation is used as fire retardant,the resin is chosen from the group of phenol-formaldehyde, in which casethe 10 aqueous solution of said fire retardant composition has a pHbetween 6.0 and 8.0. In another embodiment, the production of woodcomposite panel boards comprises the use of a polymeric isocyanate orisocyanate-prepolymer as a resin. In this case the pH of a 10% aqueoussolution of the composition according to one of aforementionedembodiments is preferably between 4.0 and 6.0, such e.g. 4.6 or 5.0.

The invention also provides a wood composite panel, comprising a fireretardant composition and a resin, whereby said fire retardantcomposition comprises at least one fire retardant agent, a pH regulatingcompound and optionally a smoke suppressing agent, whereby the pH of a10% aqueous solution of said composition lies between 3.5 and 8.5, morepreferably between 4.0 and 8.0, depending on the chosen resin. Bypreference, said panels produced by addition of a composition accordingto the current invention are medium-density fiberboard (MDF), HDF,oriented strand board (OSB), particle board or wood and cellulose fiberinsulation products. As a consequence, the current invention equallyrelates to such panels provided with the fire retardant composition asdescribed herein.

EXAMPLES

The invention is further explained, by examples which are not to be seenas limitative for the scope of the current invention.

Flame Retardant Composition Specifically Suitable for Use in ParticleBoards

-   -   MAP (monoammonium dihydrogen phosphate) 83%    -   DAP (diammonium hydrogen phosphate) 2.0%    -   Ammonium sulfate 5.0%    -   MCP (monocalcium phosphate) 5%    -   DCP (dicalcium phosphate) 2.5%    -   Ulexite (natrium calcium borate) 2.5%

pH of a 10% solution of the composition is 4.5.

Flame Retardant Composition Specifically Suitable for Use in MDF

-   -   MAP (monoammonium dihydrogen phosphate) 42.5%    -   DAP (diammonium hydrogen phosphate) 30.0%    -   Guanidine phosphate 12.5%    -   MGP (magnesium hydrogen phosphate) 10%    -   Colemanite (calcium borate) 5%

pH of a 10% solution of the composition is 6.2.

Intumescent Flame Retardant Composition Specifically Suitable for Use inOSB

-   -   ammonium polyphosphate 75.0%    -   ammonium dihydrogen phosphate 5.0%    -   melamine 8.0%    -   melamine phosphate 2%    -   vinyl acetate/acrylate dispersion 10%

pH of a 10% solution of the composition is 5.0.

Intumescent Flame Retardant Composition Specifically Suitable for WoodFibre Insulation

-   -   monoammonium dihydrogen phosphate 75%    -   melamine 15%    -   pentaerythritol 5.0%    -   titanium dioxide 5.0%

pH of a 10% solution of the composition is 4.5

Intumescent Flame Retardant Composition Specifically Suitable for Use inPlywood

-   -   guanidine phosphate 78.0%    -   phosphoric acid 12.5%    -   Di-sodium Octaborate tetrahydrate 9.5%

pH of a 10% solution of the composition is 6.0.

1. A fire retardant composition for use in wood composite panels,whereby said composition comprises: at least one fire retardant agentchosen from monoammonium dihydrogen phosphate (MAP); di-ammoniumhydrogen phosphate (DAP); ammonium polyphosphate; melamine phosphate;melamine polyphosphate; ammonium sulfate; ammonium chloride; ammoniumsulfamate; guanidine phosphate; guanidine hydrogen phosphate; guanidinesulfamate; guanidine carbonate; methylene urea, urea phosphate; alkalineearth phosphates; and any combinations thereof, whereby a totalconcentration of said fire retardant agent in the composition is between25 and 100% by dry weight of said composition, optionally at least onesmoke suppressing agent, whereby a total concentration of smokesuppressing agents is between 0 and 25% by dry weight of saidcomposition; and a pH regulating compound, characterized in that a pH ofa 10% aqueous solution of said composition lies between 3.5 and 8.5. 2.A fire retardant composition for use in wood composite panels,characterized in that said composition comprises an intumescentformulation as a fire retardant agent, wherein a pH of a 10% aqueoussolution of said composition lies between 3.5 and 8.5.
 3. The fireretardant composition according to claim 2, characterized in that atotal concentration of said fire retardant agent in the composition isbetween 25 and 100% by dry weight of said composition.
 4. The fireretardant composition according to claim 2, characterized in that saidintumescent formulation comprises a mixture of one or more acidcomponents, one or more spumific agents, a pH regulating compound andoptionally one or more carbonific components, a binding component and/oran ablative acting fire retarding component.
 5. The fire retardantcomposition according to claim 2, characterized in that a concentrationof acid components in said intumescent formulation is between 10.0 and95.0% by dry weight of said intumescent formulation, and a concentrationof spumific agents is between 0.2 and 80.0% by dry weight of saidintumescent formulation.
 6. The fire retardant composition according toclaim 5, characterized in that said acid components are chosen fromphosphoric acid, sulfuric acid, boric acid, monoammonium dihydrogenphosphate, diammonium hydrogen phosphate, ammonium polyphosphate,ammonium sulfate, ammonium halides, urea phosphate, guanyl ureaphosphate, guanidine carbonate, melamine phosphate, melaminepolyphosphate, melamine cyanurate, pentaerythritol phosphate, guanidinephosphate, other amine phosphates, and other amide phosphates.
 7. Thefire retardant composition according to claim 2, characterized in thatsaid composition comprises one or more carbonific components which arechosen from glucose, arabinose and other monosaccharides, lactose,maltose and other disaccharides, starch, cellulose, dextrin, otherpolysaccharides, sorbitol, erythritol, pentaerythritoldipentaerythritol, tripentaerythritol, other polyhydric alcohols, andother substances susceptible to dehydration or deamination, wherein saidcarbonific components are present in a concentration of between 0.05 and60.0% by dry weight of said intumescent formulation.
 8. The fireretardant composition according to claim 5, characterized in that saidspumific agents are chosen from melamine, melamine cyanurate, melaminephosphate, melamine polyphosphate, other melamine-based compounds,guanidine phosphate, guanidine sulfate, guanidine carbonate, and otherguanidine salts.
 9. The fire retardant composition according to claim 2,further comprising a binding component, wherein the binding component ischosen from acrylate, styrene-acrylate, vinyl acetate, vinylacetate-ethylene, polyvinylethers and polyurethanes.
 10. The fireretardant composition according to claim 2, further comprising anablative acting fire retarding component, wherein the ablative actingfire retarding component is chosen from aluminum hydroxide, aluminumoxide hydroxide, magnesium hydroxide, titanium dioxide, colemanite,ulexite and other ablative acting substances.
 11. The fire retardantcomposition according to claim 2, characterized in that the pH of a 10%aqueous solution of said composition lies between 5.0 and 7.0 when saidcomposition is used in wood composite panels comprising aurea-formaldehyde resin.
 12. The fire retardant composition according toclaim 2, characterized in that the pH of a 10% aqueous solution of saidcomposition lies between 4.0 and 6.0 when said composition is used inwood composite panels comprising an isocyanate resin.
 13. The fireretardant composition according to claim 2, characterized in that the pHof a 10% aqueous solution of said composition lies between 6.0 and 8.0when said composition is used in wood composite panels comprising aphenol-formaldehyde resin.
 14. The fire retardant composition accordingto claim 1, wherein the composition includes the smoke suppressingagent, wherein said smoke suppressing agent is chosen from borateminerals, boric acid or a salt thereof, calcium or magnesium phosphatesand magnesium hydroxide or a mineral thereof.
 15. The fire retardantcomposition according to claim 4, characterized in that said pHregulating compound is chosen from monoammonium dihydrogen, diammoniumhydrogen phosphate, guanidine phosphate, guanidine hydrogen phosphate,guanidine carbonate, ammonium or aluminum sulfate, magnesium phosphate,magnesium ammonium phosphate, monoethanolamine, phosphoric acid,sulfamic acid, magnesium phosphate, mono- or dicalcium phosphate, mono-,di-, trialkali metal phosphates, ammonia or ammonia solution, melamine,and combinations thereof.
 16. The fire retardant composition accordingto claim 4, characterized in that said pH regulating compound acts as afire retardant and is chosen from ammonium (poly)phosphates and ammoniumsulfate.
 17. The fire retardant composition according to claim 4,characterized in that the total concentration of said pH regulatingcompound is between 2 and 60%.
 18. The fire retardant compositionaccording to claim 14, characterized in that said borate minerals areulexite, colemanite, kernite, howlite or probertite.
 19. The fireretardant composition according to claim 2, characterized in that saidcomposition is in a powder or liquid form.
 20. The fire retardantcomposition according to claim 2, further comprising a thickener and/orviscosity regulator.
 21. The fire retardant composition according toclaim 2, whereby said composition comprises a detection compound and/oran antimicrobial or antifungal compound.
 22. Use of the compositionaccording to claim 2 in wood composite panels, whereby said compositionis mixed with or sprayed upon cellulose containing material prior tosaid cellulose containing material being pressed to a panel in thepresence of a resin.
 23. A method for the production of wood compositepanels comprising the fire retardant composition according to claim 2,characterized in that said fire retardant composition is added tocellulose based strips, chips or particles by spraying or mixing.
 24. Awood composite panel, comprising a fire retardant composition accordingto claim 2 and a resin whereby said resin is chosen fromurea-formaldehydes, isocyanates and phenol-formaldehydes.
 25. The woodcomposite panel according to claim 24, characterized in that said woodcomposite panel is a medium-density fiberboard (MDF), high densityfiberboard (HDF), oriented strand board (OSB), particle or panel board.